Navigation Links
Why chromosomes never tie their shoelaces
Date:9/8/2010

In the latest issue of the journal Nature, Miguel Godinho Ferreira, Principal Investigator at the Instituto Gulbenkian de Cincia (IGC) in Portugal, lead a team of researchers to shed light on a paradox that has puzzled biologists since the discovery of telomeres, the protective tips of chromosomes: while broken chromosome ends generated by DNA damage (such as radiation or cigarette smoke) are quickly joined together, telomeres are never tied to each other, thus allowing for the correct segregation of the genetic material into all cells in our body. Since telomeres erode in response to the continuous cell divisions in our body, this protective function fades away as we grow older. Complete loss of telomeres results in sticky chromosome-ends that join to each other creating to genetic chaos the very initial steps of cancer. Understanding how the tips of the chromosomes are protected from DNA repair and how the cells respond when they are unprotected will provide insights into the initial stages of tumourgenesis, ageing and future therapeutic interventions.

Cells respond to broken or damaged DNA by arresting their cell cycle while the damage is repaired. If the tips of chromosomes were recognized as broken DNA, cells would be constantly trying to mend the ends of chromosomes, leading to cell death and mutations in the DNA. Telomeres - the caps made up of protein and DNA at the tips of chromosomes - stop this from happening.

Through a series of meticulous experiments the Portuguese team, in collaboration with researchers at University of Illinois, Chicago, reveal that the crux lies in the changes of a protein, a Histone modification, located close to the telomeres. Histones are found along the entire length of all chromosomes, helping to package the DNA and also playing a role in regulating gene activity. Using fission yeast (used to make bread and beer) as a model organism, the researchers found that one of the Histones neighbouring the telomeres lacks a chemical signal, thus rendering the DNA damage recognition machinery incapable of arresting the cell cycle.

Says Miguel Godinho Ferreira, 'It's amazing, but it appears to be this single change that underlies the cell's ability to distinguish the end of the chromosome (i.e. a telomere) from a break in the middle. Indeed, along the rest of the genome, these Histones retain the chemical signal, so that when DNA damage does occur in any of these regions, DNA repair is set up and broken ends joined together.'

Telomeres are like the plastic caps on shoelaces: just as a shoelace starts unravelling when the cap is lost, so chromosome ends would become shorter with each cell division were it not for the telomeres. Telomeres are added or elongated by the enzyme telomerase. However, most cells in our body lack telomerase from when we are born, consequently telomeres become shorter and lose protection, sending signals for cells to stop dividing and start ageing. In about 85% of cancers, cells re-activate telomerase, contributing to their ability to divide and proliferate.

Even though DNA repair must be prevented at telomeres, assembly of the DNA damage recognition machinery is vital for telomerase activation and telomere elongation. Miguel Godinho Ferreira adds, 'Eukaryotic cells have evolved a very specific mechanism whereby telomerase recruitment goes ahead undisturbed, yet the whole DNA repair process is kept at bay from chromosome ends. Knowing the details of telomere capping is crucial to understanding its relationship to cancer, ageing and several diseases, and the multiple ways in which telomere manipulation may, potentially, lead to effective treatments".

He continues emphasizing the importance of fundamental basic research: "When Liz Blackburn, Carol Greider and Jack Szostak discovered telomerase and telomeres in the 80s, for which they got last year's Nobel Prize in Physiology or Medicine, they were searching for a solution to the "end-replication problem" and far from imagining the clinical implications these findings are currently developing. They were simply solving an academic puzzle created by the discovery of the double helix and the inability of DNA polymerases to synthesize the ends of linear DNA. Likewise, we are honored and excited to contribute to unravel these mechanisms, but perfectly aware that the direct implications of this work are still many years away".


'/>"/>

Contact: Silvia Castro
sacastro@igc.gulbenkian.pt
351-214-464-537
Instituto Gulbenkian de Ciencia
Source:Eurekalert  

Related medicine news :

1. Infectious Virus Hides In Human Chromosomes During Latency And Can Be Passed From Parents To Their Children
2. Womens Chromosomes May Affect Blood Pressure
3. Enterprise PDM Integration has Never Been Easier; Zero Wait-State Announces Leading SolidWorks Reseller GoEngineer as Master Distributor for DesignState
4. Gene is linked to lung cancer development in never-smokers
5. Business Book Author is Breaking All the Rules and Utilizing Social Media in a Way that Has Never Been Done Before
6. Ross Nanotechnology Corporation Introduces the NeverWet™ Coating on its First Consumer Product – The Clear-n-Clean Plunger
7. Global Basecamps Launches New Website: Researching and Booking Sustainable Travel Has Never Been Easier
8. Revolutionary Sports Bottle Unscrews at Both Ends for Easy Cleaning -- Never Deal With Stinky, Moldy Bottles Again
9. 1 in 4 Californian children have never seen a dentist, study finds
10. Phonak Asks Young FM Users to Tell Their Stories on YouTube
11. Luth Researchs IndicatorEDG(TM) Study Finds Americans Hopes of Achieving Their Dreams Are Fading
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Why chromosomes never tie their shoelaces
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... The temporary closing of Bruton Memorial Library ... City Observer , brings up a new, often overlooked aspect of head lice: the parasite’s ... for fumigation is not a common occurrence, but a necessary one in the event that ...
(Date:6/25/2016)... , ... June 25, 2016 , ... ... and non-athletes recover from injury. Recently, he has implemented orthobiologic procedures as a ... area —Johnson is one of the first doctors to perform the treatment. Orthobiologics ...
(Date:6/24/2016)... ... June 24, 2016 , ... Those who have experienced traumatic events may ... to unhealthy avenues, such as drug or alcohol abuse, as a coping mechanism. To ... for healthy coping following a traumatic event. , Trauma sufferers tend to feel a ...
(Date:6/24/2016)... ... , ... Global law firm Greenberg Traurig, P.A. announced that 20 Florida attorneys ... peers for this recognition are considered among the top 2 percent of lawyers practicing ... members of this year’s Legal Elite Hall of Fame: Miami Shareholders Mark D. ...
(Date:6/24/2016)... ... 2016 , ... People across the U.S. are sharpening their pencils and honing ... contest in which patients and their families pay tribute to a genetic counselor by ... Society of Genetic Counselors (NSGC) Annual Education Conference (AEC) this September. , In ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... DUBLIN , June 24, 2016 ... and Markets has announced the addition of the ... their offering. ... products and provides an updated review, including its applications ... covering the total market, which includes three main industries: ...
(Date:6/24/2016)... BEIJING , June 24, 2016 Dehaier ... or the "Company"), which develops, markets and sells medical ... China , signed a strategic cooperation agreement with ... as "Hongyuan Supply Chain") on June 20, 2016, to ... Under the strategic cooperation agreement, Dehaier will leverage Hongyuan ...
(Date:6/24/2016)... , June 24, 2016 According ... by Type (Standard Pen Needles, Safety Pen Needles), Needle ... GLP-1, Growth Hormone), Mode of Purchase (Retail, Non-Retail) - ... This report studies the market for the forecast period ... reach USD 2.81 Billion by 2021 from USD 1.65 ...
Breaking Medicine Technology: